9.1 whats-new & upgrade guide

[felixpalmer]

For #9056

Change List

• update whats-new
• update upgrade guide

[coveralls]

coverage: 91.701% (-0.001%) from 91.702%
when pulling 516ef4b on felix/whats-new-9.1
into e9eada6 on master.

[ibgreen]

Can we also remove the experimental status on _GlobeView, and mention that here? @Pessimistress

This looks a bit cluttered, referencing issues rather than docs etc.

Suggested change

	MapLibre v5 recently launched a [globe view](https://github.com/maplibre/maplibre-gl-js/issues/307), and in collaboration with the MapLibre team, we have add support for seamlessly integrating deck.gl layers with the globe using the existing [GlobeView](./api-reference/core/globe-view). The integration works for all three [Intergration Modes](./developer-guide/base-maps/using-with-maplibre#integration-modes).
	- The deck.gl [`GlobeView`](./api-reference/core/globe-view) now integrates seamlessly with the MapLibre v5 [globe view](https://maplibre.org/roadmap/globe-view/).
	- The Maplibre globe view integration was done in close collaboration with the MapLibre team, and works for all three [Basemap Intergration Modes](./developer-guide/base-maps/using-with-maplibre#integration-modes).
	- The deck.gl `GlobeView` is no longer considered experimental, and can now be imported without a leading underscore.

[ibgreen]

Suggested change

	deck.gl v9.0 added support for widgets, with v9.1 they can now be defined in React. All of our built-in widgets are now react-compatible and available from the `@deck.gl/react` package. To try it out, check out our new [getting started example](https://github.com/visgl/deck.gl/tree/master/examples/get-started/react/widgets) for widgets in React.
	deck.gl v9.0 added support for widgets, with v9.1 users can now create React components with the same level of deep deck.gl integration.
	- All the official deck.gl widgets can now be easily wrapped into React components with the new `useWidget` hook.
	- Pre-wrapped React components for existing widget are available from the `@deck.gl/react` package.
	- To try it out, check out our new [getting started example](https://github.com/visgl/deck.gl/tree/master/examples/get-started/react/widgets) for using widgets in React.

[ibgreen]

Suggested change

	A major benefit of React support is the ability to define custom widgets with UI built in React in your own applications. Learn how to write your own deck.gl widgets with our new [Custom Widgets Developer Guide](./docs/developer-guide/custom-widgets).
	deck.gl v9.1 provides the ability to for applications to write React component that integrate with deck.gl using the widget interface. Learn how to write such React components with our new [Custom Widgets Developer Guide](./docs/developer-guide/custom-widgets).

[ibgreen]

Suggested change

	- luma.gl has been updated to v9.1 which focuses on building out WebGPU support. For details see [release notes](https://luma.gl/docs/whats-new#version-91-in-development) and [upgrade-guide](https://luma.gl/docs/upgrade-guide#upgrading-to-v91).
	- luma.gl has been updated to v9.1 which focuses on improved WebGPU support. For details see [release notes](https://luma.gl/docs/whats-new#version-91-in-development) and [upgrade-guide](https://luma.gl/docs/upgrade-guide#upgrading-to-v91).